During the commercial break of your favorite television show, the advertisements that play out in front of you don’t just influence your opinions of companies and shopping habits; the ads also could affect how your body responds to drugs. Watching a positive, rather than negative, ad for the allergy drug Claritin after taking a dose makes the pill more effective at altering the body’s immune response, researchers report today in PNAS Early Edition.
“Every day, we are exposed to a high number of advertising messages,” says economist Emir Kamenica of the University of Chicago, first author of the new paper. “And these messages may influence not only whether we buy a product, but also how our body works.”
Since the dawn of modern medicine, doctors have known (and sometimes taken advantage of the fact) that patients who believe they are being given an effective drug or therapy—even if it’s a sugar pill—will often have a better reaction than those who are skeptical of the drug. But the so-called placebo effect is still poorly understood and hard to study. Kamenica wondered whether this link between someone’s beliefs about a medication and its efficacy played out not only in the doctor’s office, but in front of the television.
“It doesn’t happen on a daily basis that a doctor gives you a sugar pill and bends the truth about what it is,” he says. “But we are constantly bombarded with advertising, often without consent.”
To test the link between advertising and how well a drug works, Kamenica and his collaborators needed to find a fast-acting drug that they could measure the effects of immediately in the lab. Otherwise, ads could influence a patient’s outcome by changing his or her likelihood of taking the medication or affecting other behavior, such as diet and exercise. So the researchers turned to Claritin.
Claritin is an antihistamine medication; it works by blocking histamine molecules which are produced by the body when it senses an allergen like pollen or dust. By blocking histamine, Claritin and other antihistamines diminish the swelling, itching, or sneezing that normally results. How well an antihistamine like Claritin works can be gauged not only by asking patients about their sniffles and itches, though, but with a more quantitative measurement: how the body responds to histamine that’s injected into the arm. The better Claritin works, the smaller the swelling from such an injection will be.
Kamenica and his colleagues studied 340 people, some with known allergies and some without. Each person received an injection of histamine in their forearm, and the response was measured. Then, they received a dose of Claritin, were told what it was, and watched a movie interspersed with ads—either positive Claritin ads, or ads for a competing allergy drug, Zyrtec, which spoke negatively about Claritin. Next, the histamine injection was repeated and the size of the swollen “wheal” once again measured.
For all patients, taking Claritin led to a smaller wheal. In those with known allergies, which ads were watched had no difference on the size of the wheal after Claritin treatment—in either case, it was 28 percent smaller. But in those who had no diagnosis of allergies, taking Claritin and watching Claritin ads reduced the wheal by 31 percent, while taking Claritin and watching Zyrtec ads made the wheal only 25 percent smaller.
“Perhaps people who don’t have allergies are more uncertain about what antihistamines are like, or they may have paid less attention to ads for such drugs in the past, so their beliefs about Claritin are more malleable,” Kamenica explains.
Indeed, when he compared subjects’ views about Claritin before and after watching the ads, those without allergies had a greater change in opinion from the ads. And the greater their change in opinion about Claritin was, the smaller the wheal was after the ads.
“There’s been a big debate about the potential consequences of direct advertisement of drugs to consumers,” says Kamenica. “We’re injecting into that debate an entirely novel idea, that such advertisements can actually change drug efficacy.”
The data doesn’t distinguish whether the positive Claritin ad increased the efficacy of the drug or whether the Zyrtec ad, with negative sentiments on Claritin, decreased the efficacy. The researchers hope to clarify that in future studies. And
as for whether advertising affects other drugs in a similar way, that can only be hypothesized. But Kamenica says there’s no reason to think the phenomenon would be unique to Claritin. Based on the difference in ad responses between those who had allergies, and were likely more familiar with Claritin to begin with, Kamenica thinks that the less someone knows of a drug to begin with, the more an ad can influence their response to it.
“With a drug that no one has heard of, you might get an even bigger effect,” he says. “Because your opinions on that drug would be even more malleable.”